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What is Semaphore, what is significance of .sem file created?

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Please explain with real life example?

posted Jun 22, 2014 by Amit Kumar Pandey

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A semaphore is a variable or abstract data type that is used for controlling access, by multiple processes, to a common resource in a parallel programming or a multi user environment.

When used for a pool of resources, a semaphore tracks only how many resources are free; it does not keep track of which of the resources are free. Some other mechanism (possibly involving more semaphores) may be required to select a particular free resource.

For example someone facing the error while locking the file by using the pvcs client tool. But able to lock the file using the unix command line.
here is my error receives:
Version Manager could not create the semaphore "\PVCS_CBM-CUSTOMIZING\archives\CBM-CUSTOMIZING\CbmDfa\GRAND_TOT_OUT_RES_GER.DFA-arc" for this project. The semaphore may already exist or the location may be invalid.

Here .sem file has been created in that location we need to delete the .sem there after that you can able to lock or any process on that file.

answer Jul 6, 2014 by Kali Mishra
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